Apparatus for grinding coal.



' PATENTED JUNE 16, 1908. T. A. EDISON. APPARATUS FOR GRINDING GOAL.

APPLIOATION FILED NOV. 27, 1906.

a SHEETS-SHEETA.

PATENTED JUNE- 16, 1908. T. A. EDISON. US FOR GRINDING GOAL.

APPARAT APPLICATION FILED NOV. 27, 1906.

3 SHEETS-SHEET 2.

w N Z w v W a x M QN. I N m T f z NE 1+ \X MN NM H N :m N mm m. u n. u v u. 0 M A 6 \Q Q e u w M a m u k w M v %N N fi 3 SHEEISSHEET 3.

PATENTED JUNE 16, 1908.

"MAX.

z awiziarz,

T. A. EDISON. APPARATUS FOR GRINDING GOAL. APPLICATION FILED NOV 27, 1906 j AA THOMAS A. EDISON, OF LLEWELLYN PARK, ORANGE, NEW JERSEY.

APPARATUS FOR GRINDING COAI Specification of Letters Patent.

Patented June 16, 1908.

Application filed November 27, 1906. Serial No. 345,329.

To all whom it may concern:

Be it known that I, THOMAS A. ED1soN,'a citizen of the United States, residing at Llewellyn Park, Orange, county of Essex, and State of New Jersey, have invented cer- .tain new and useful 1m rovements in Apparatus for Grinding Qoa of which the folowing is a description.

My invention relates paratus for the fine grinding of coal preparatory to use in connection with fireboxes and other industrial apparatus.

At the resent time the fine rinding of coal is per ormed in tube mills, ba 1 mills and Griffin mills, the sizing of the articles being efiected by screening devices through which air currents carrying the fine particles, are slowly circulated. Apparatus of this sort is extremely slow in operation and a plant of any considerable capacity occupies a relatively enormous space.

The object of myinvention is to provide an a paratus for the fine grinding of coal in whic the reduction is eflected by means of grinding rolls and in which the sizing is secured by means of air blasts, whereby the apparatus will be'verycompact, of enormous capacity compared with the present devices, and in which the grinding of the coal can be carried on in entire safety and without danger of explosion.

To this end the invention comprises a air of grinding rolls for reducing the coal, w ich latter is allowed to fall or flow substantially at right angles to an air blast, whereby the finer portions of the coal will be blown out, after which the air currents with their load of fine articles are directed to a suitable" settling chamber and filtering device, by means of ,which the solid particles will be separated from the air.

Preferably, the apparatus is of such a character that the particleslwhich are sufiiciently small to be carried off by the air blast, but which are too coarse for the intended use, will be returned automatically to the grinding rolls for further reduction. Also, the ap aratu's preferably comprises one or more sett ing 'hambers in which much of the impalipable dust will settle before-reaching the ii tering devices,'which dust will be automatically carried to a suitable stock house, or other oint of storage. The filter which I preferab y use for the purpose is one having automatically renewable filtering media, whereby the resistance to the passage to an improved aprindin t e coal of the air currents will remain constant, so that the effect of the blastwill be uniform at all times. Such a filtering operation can be obtained by causing the air currents to pass through filtering walls or partitions, formed of a slowly moving load of granular material,

such as'coarse sand or crushed cement rock, the particles of which vary in diameter from to of an inch. Provision is made for separating from the granular material, the load of im alpable coal dust, mechanically separated thereby from the air currents, and the dust so se arated will'be automatically forwarded to t e stock house or other point of deposit.

In order that the invention may be better understood, attention is directed to the accompanying drawings, forming part of this specification, and in which- Figure'l is a side elevation of the apparatusin its referred form, Fig. 2 is a longitudinal sectional View, of a portion of the apparatus on an enlarged scale, tal sectional view, illustrating the several conveyers, Fig. 4, a cross sectional view.on the line 44 of Fig. 2, and Fig. 5, a similar view on the line 5-5 of Fig. 3.

In all of the above views corresponding parts are represented by the same numerals of reference.

12 re resent two supplied thereto from a hopper 3, by means of a roller feed 4. From the grinding rolls the material falls into a hopper 5, from which it is fed. by a roller feed 6, in a sufficiently wid'e stream, so as to flow over the inclined shelves 7-7. These shelves are located in a blast chamber 8, su plied with an air blast from ablower 9. Ti fe air currents in passing through the channels between the inclined shelves 7, will carry off the sufficiently fine particles into the settling and filtering devices, the velocity of the blast being suitably adjusted for this purpose. The coarse particles which are not carried off by the blast fall into a hopper 10, fromjwhich they'are conve ed by a conveyer 11, to the boot 12, of an e evator 13, by which they are elevated to the hopper 3 to a ain pass through the crushing or grindin ro s, as will be understood. From the b ast chamber 8', the air currents carrying the solid particles of coal, enter the settling chamber 14, formed between two screens 15-15, of suflicient fineness of mesh to separate the particles. which are too coarse for effective use, and

Fig. 3, a horizongrinding rolls for devices. posited 1n which require'to be returned to the grinding The particles which thus are dothe settling chamber 14, are automatically removed from the same by a conveyer 16, leading to the hopper 10. The settling chamber 14 is of large size, so that the velocity of the air currents entering the same will be checked, permitting the deposit I setting chambers 17.

. which is 1 which leads to the vertically downwards and air currents will leave of theparticles which are too large, and allowing the air currents carrying the fine dust to ass slowly through the screens 15 into Inthese latter settling chambers, a considerable portion of the fine dust will settle by gravity and will be carried off by conveyers 18, which pass through the rear wall of the filtering apparatus anddeposit the dust in engagement with a convey'er 19 located in a pipe 20, and leading to a suitable stock house, or other point of deposit.

The outer walls of the two settling chambers 17 comprise the filtering medium, preferably composed of a slowly moving load of relatively coarse particles, such as coarse sand or ground cement rock, which material is supported by the inclined shelves 21, and is kept in slow movement by roller feeds 22. The load of coarse-particles comprising each filter presents innumerable tortuous channels through which the air will be allowed to seep slowly and within which the impalpable dust will be se arated. The filtering material with its loa of separated dust slowly fed downwardly by the roller feeds 22, is delivered onto conveyers 23, and

is carried to the rear of the apparatus and deposited in the boots 24 of elevators 25. The elevators 25 carry the coarse material with the fine dust mechanically entrained therewith, and deposit the same on a plurality of screens 26 by which the fine material will be separated from the coarse material. The screening operation can be very perfect, because of the great difierence in size between the coal dust and the coarse material; From the screens 26 the dust falls into a chute 27, conveyer 19, by which the fine dust will be carried to the stock house. The-coarse particles passing over the screens 26 will be deposited in the chutes 28, and. by the conveyers 29 will be again distributed over the inclined shelves 21, to again pass effect a filtering operation.

If desired, the circulation of the air currents may be facilitated by connecting an exhaust fan 30, with the filtering apparatus outside of the two filtering walls, as shown.

It will be seen that the apparatus is entirely automatic in character and by using settling chambers and filters as explained, a

very perfect separation of the fine dust from the alr'currents can be effected, so that the the apparatus in an entirely safe condition. Furthermore, the entire apparatus can be completely sealed in,

so as to reduce the danger to the minimum.

By using grinding rolls for the rinding of the coal, I am enabled to hand e enormously greater loads of material than would be possible with tube mills or Griffin mills, so that the apparatus may be made extremely com act. p Having now described my invention, what I claim as new and desire to secure by Letters Patent is as follows:

1. In apparatusfor grindingcoal, the combination with suitable grinding devices, means for presentingthe ground material to the effect of a blast of air, whereby the finer portions of the ground material will be separated therefrom, a settling chamber in which a portion of the fine particles will be separated from the air currents by gravity and a filter comprising a constantly moving wall of granular material presenting a constant resistance at all times, substantially as and for the purposes set forth.

2. In apparatus for grinding coal, the combination with suitable devices for grinding the coal, means for presenting the same to the effect of an air blast, amain settling chamber to which the air currents with their load of fine particles are directed, and in which the coarser portions of such particles will be separated by gravity, a screen through which the air currents ass from said settling chamber, and an auxi iary settling chamber in which a portion of the fine dust will be separated by gravity, a filter through which the air currents pass and in which the remaining portion of the fine dust will be separated, and means for returnin the material accumulating in the main sett ling chamber to the grinding devices, substantially as and for the purposes set forth.

3. In apparatus for-grinding. coal, the combination with suitable devices for grinding the coal, means for presenting the same to the effect of an air blast, a main settling chamber to which the load of fine particles are directed, and in which the coarser, ortions of such particles will be separated by gravity, a screen through which the air currents pass from said settling chamber, an auxiliary settling chamber in which a portion of the finedust will be separated. ravity, and a filter comprising a moving-waif of granular material havin a constant resistance at alltimes, substantially as and for the purposes set. forth. I

4. An apparatus for grinding coal, co prising in combination a pair of grinding re] s or grinding the coal, means for presenting the ground coal to the effect of an air blast by which the finer portions thereof will be carried off, a main settlin chamber, screens constituting the side wa s of said settlin chamber, and a filter outside of each of said screens, substantially as and for the purposes set forth.

5. An apparatus for grinding coal, comprising in combination a pair of grinding rolls for grinding the coal, means-forpresenting the ground coal to the effect of an air blast by which the finer portions thereof will be carried off, a main settling chamber, screens constituting the side walls of said settling, chamber, a filter outside of each of said screens, and means for returning material deposited in the settling chamber to the grinding rolls, substantiallyas and for the purposes set forth. 4

7 An apparatus for grinding coal,, comprising in combination a pair of'grinding rolls for grinding the coal, means for presenting the ground coal to the effect of an air blast, whereby the finer portions will be separated, a main settling chamber into which the air currents with their load of fine material are directed, screens constituting the side walls of said main settling chamber, an auxiliary settling chamber outside of each of said screens, and a filter constitutingthe outer wall of, each auxiliary settling chamber, substantially as and for the purposes setforth.

8. An apparatus for grinding coal, come prising in combination a pair of grinding rolls for grinding the coal, means for presenting the ground coal to the effect of an air blast, whereby the finer portions will be separated,

I a main settling chamber into which the air currents with their load of fine material are directed, screens constituting the side walls of said main settling chamber, an auxiliary settling. chamber outside of each of said screens, and a filter comprising a moving wall of granular material presenting a constant resistance and constituting the outer wall of each auxiliary settling chamber, substantially as and for the purposes set forth.

9. An apparatus for grinding coal, comprising in combination a pair of grinding rolls for grinding the coal, means for presenting the coal to the effect of an air blast, and a filter to which the air currents with their load offinematerial are directed and constituting a wall or partition of coarse material, substantially as and for the purposes set forth.

10. An apparatus for grinding coal, comrising in combination a pair of grinding rolls or grinding the coal, means for presenting the coal to the efiect of an air blast and a filter to which the air currents with their load of fine material are directed and constituting a wall or partition of coarse material, and means for keeping the coarse material in slow movement, substantially as and for the purposes set'forth.

11. An apparatus for grinding coal, comprising in combination a pair of grinding rolls or grinding the. coal, means for presenting the coal to the efiect of an air blast, and a filter to which the air currents with their load of fine material are directed, constituting a ,wall or partition of coarse material means for keeping the coarse material in slow movement, and means for screening the fine dust accumulated by the coarse material and for returning the coarse material to the filter wall, substantially as and for the purposes set forth.

This specification signed and witnessed this 23rd day of November 1906.

THOMAS A. iinisou.

Witnesses:

FRANK L. DYER, ANNA R. KLEHM. 

